Lock cylinders with rotary disc tumblers have proven superior in the prevention of serruptitious entry means. This type of cylinder is gaining wide acceptance due to the relative ease of picking other types of cylinders.
The design and manufacture of keys of unique construction is a desirable element in the advancement of the art.
Unique key constructions that will operate bi-directional rotary disc-tumbler cylinders as in Roberts, et al U.S. Pat. No. 3,789,638 are in demand and will advance the state of the art as to this type of cylinder.